The conventional pushup exercise has traditionally been used for strengthening arm muscles. A conventional pushup is performed by lying face down with palms to the floor and by pushing the body up and down with the arms.
Many types of handgrip devices are known for performing pushups. For example, Acs et. al, U.S. Pat. No. 3,115,338, disclose handles that are rigidly supported on stationary bases. The handles assist the user performing pushups by providing a more adaptable and natural hand gripping position. The handles allow the user to keep a straight wrist rather than a bent wrist. The handles also elevate the user's hands relative to the floor, thereby increasing the range of motion through which the user moves during the pushup exercise.
Other handgrip devices provide additional features to improve the muscle conditioning effect of performing pushups. For example, Swisher, U.S. Pat. No. 5,205,802, provides an elongate, elevated base and two hand grips. The invention allows the user to adjust the lateral space between grips for maximum comfort and to vary the range of motion of the exercise. Further, the hand grips are rotatable so that the user can rotate his hands and wrists through a mechanically limited range of motion.
Hill, U.S. Pat. No. 4,610,448, also discloses hand grips for performing pushups. The hand grips allow the user to rotate his hand about a horizontal axis in order to position the wrist at a comfortable position, and about a vertical axis in order to simultaneously rotate the arm while extending and contracting it.
Several of the devices in the prior art allow the user to rotate his hands about a vertical axis while performing pushups. Such devices comprise rotatably-connected, planar plates that are arranged in contact with one another. To rotate such devices, the user must overcome the frictional force between the plates, which may be excessive depending on the upper body weight of the user and the coefficient of friction between the plates. Further, rotation of the device may not be smooth due to variations in the force required to initiate rotation compared to the force required to maintain rotation. Therefore, it would be desirable to provide hand supports that can be easily and smoothly rotated about a vertical axis while performing pushups.
Several of the pushup devices in the prior art provide a handle having a cylindrical profile, which may be comfortable for some users but uncomfortable for others. Therefore, it would be desirable to provide a pushup device that has a plurality of interchangeable handles having grip profiles that are different from one another.
In the prior art, the various pushup devices vary greatly in size and complexity. However, even the smallest devices are prohibitively large to conveniently travel with in a briefcase, handbag or small luggage. Therefore, it would be desirable to provide a pushup device that is easily collapsible to a compact size so that the user can comfortably travel with the device.